Jet-accelerated armor-piercing bomb



March 13 1951 c. N. HlcKMAN Erm.

JET-ACCELERATED ARMOR PIERCING BOMB 4 Sheets-Sheet l Filed Feb. 9. 1945 March 13, 1951 c. N. HICKMAN Erm. 2,545,204

JET-ACCELERATED ARMOR PIERCING BOMB Filed Feb. 9, 1945 4 sheets-sheet :a

46a 7a as 5d 84 a5 46a INVENTORS LARE/VE IV, H/KMV BY RUDOLPH/r. MALL/H March 13, 1951 c. N. HICKMAN Erm. 2,545,204

JET-CCELERTED ARMOR PIERCING BOMB Filed Feb. 9, 1945 4 Sheets-Sheet 3 a MAA ZZM W//M su WHA@ m d 3// VMM T 6 4 Q .mEEL um March 13, 1951 c. N. HlcKMAN ET AL JETAccELERATED ARMOR PIERCING BOMB 4 Sheets-Sheet 4 Filed Feb'. 9, 1945 lNvENToRs GRUMlV/V. ATORNEYk i CLARE/VCE' IV. HIC/(MAN RUDULPH MALL/NA RAYMOND L.

yPatented Mar. 13, 1951 'JET-,AGCEIJERATED ARMOR-PIERGNG 0BOMB Clarence N. Hickman, Jaokson'iHelLghts, AN. il., -Raymond .,L. .-(raumann, Alexandria, Ma., ,and RudolphLF. Mallna, Hastings, N. Y.; said Hikthe 2,545,204 "QFFJCE man and said -Graumann Aassignors UnitedStates'o America as representedfby-the 4Secretary of A'the fNavy, and said M-allina as- -signor to VBell Telephone Laboratories, AIncorporatedyNewiYork, N.

York

y.Apnlirmtion Eehruary 9, 1945, :SerialN041577i0'114 'i lThis invention relates to an improved `4ietaccelerated `armor piercing projectile, :such V as a bomb, and more particularly tdaprojectileof 4this type having novelmeans for armirigthejet propellant of theo lzvrojectile and for l.igniting the `propellant after a l.time delay following launching of the, projectile.

Modern armor `piercing bombsmust ordinarily be dropped from a `very-.high altitudezinor'der to attain a `,striking velocity-sufcientlylargevto cause the bomb,togpenetratepthethickarmor of battleships or otherfarmoredtargets. ,Itis well known that bombing accuracy Hdecreases with altitude and that clouds-and darkness frequently make it impossible `to .see the 4target .from Van altitude at Whiehthesebombsrnust bedropped :if their armor-piercingfqualities areltorbe effective. A `jet impulsewprovidesta suitablemeans jfor vincreasing 1 the --Velocity of bombsV dropped -at :relativelyrlow altitudes. This ietinipulseisproduced byl the rapid ejection otgasesfroma fast- `burning propellant powder `vthrough a .suitable nozzle attached tothebody ofthe bomb.

Llln La bomb; provided with a jetv impulseaccelermating device, it is necessary to eontrolaccurately the Apoint ofgjet initiation inethe trajectory,in order notito decrease the accuracyofthe bomb.

` By` initiating the jet ,atga .point' in fthe-normal `.trajectory :of the bombzlat which ,the lateral com- :ponent of .the vr.thrust 1: ro duoed by l the .jet lis` lat fa minimum, it isjpossi-ble to increasethe-,velocity `of the bomb :with aa minimum change in its `-.nor-mal trajectory.

-Qne object of this inventionVthereforalislvto provide van improved V.jet-accelerated bomb 2or 'H other projectile having EnovelA ,means I forarming theV jet propellant and forigniting it at ,apredetermined point in .the normal trajectoryY ofthe projectile, softhat'its normal trajectory' is sub- 'stantially preserved.

Another objectof this inventionis to'provide an 4improved jet-accelerated armor-piercingbomb having a combustioncharnber secured to thetail of v the bomb and having ajdevicefor arming the .bomb and' the jet propellant ignitingfdevic and forfiiring the jetpropellant. In a preferredl form of the bomb `the device' `is mounted in theffnozzle ofthe combustion ehamberand is 'ejected 'to-'clear the jet` by pressure of the vcomlmstion gases develpped'inl'the chamber-on ignition of'fthe.

propellant powder.

AAnother object of 'the inventionn is'tojprovide an arming `device of the charactergreferredto above in whiehthefuzefor detonatingthehigh r explosive `oi'fthe :bombis Yarmed arten the-proi2 rjectile fis launhe's even theush Athe enacte- 'lerating device fai'ls`to `becomeignitecl.` i

.Ammer Obiect 0f ,thenventipn iS t0 pmvde Ya1:1evirze10f.the .characterreferred' t0 .abovewliieh 'has safetynieans for preventing arming .of the `iet propellant' ,igniiine .dense .even thugh .the

fuze 'for the high er-plasir@ 0f 'the projectile beomesiaeidentally.armed f` A ifurther object of u:this invention @is to y: promum "change iin .the muriel 'naieciely 0f libe projectile In a projeiile'mede .ac .eldngflo the invention, .tbeembuston.member is eiled gto jtlie tail Aof fthe `projewotile s o VAas to contorni Athe spacev within the nozzle-conirnriniating with the ,combustion chamber isrsirablrzusedfbr retaining .the armipeaerire meibanm .of the jet, this Ymechanism Lbeing -ejected-it pelear 20 the jet bythevpressure developed withinjthe combustiorrl'ianfrberjof'jhe accelerator. T he mechanism is mconstrnctewri; to delay ignition iof: the'fjet propellantjpowderas desiree; Soi aS Suizsleially to preserve the jnorrnal trajectory `ofthe` pro- Another object oftheiinvention'is to provide a means-'for sealing'the f uze for the Lhighfexplo- :sive of the bomb from thejhotf propellant gases in `the;combustion chamber;andfstilljperrnitting .glf this-fum to ,bearmedbnamethanismfextendieg through the combustion ghamben It has beenjfound `Itliatftlie arming Wire which normally extends through "jpropeller rvaries ^of bomb fuzes to prevent 'rotationthereofis'not completely reliableas the sole lsafety element-for the` jet-propellingeoharge'in the bo'rnb. fThiswill ybe "apparent once itis -eonsidered-that prior to loadinguthese-bombs v-on airplanes, the lllsaombs e frequently'V Jlie exposed upon-thei-drecks vof` aircraft 40 carriers in a position whereshelldragmentsdor the like 1 may :easily fdislo'dge the .iarming ...wire from44 its position of :secur-ng l engagement with theepropeller-vanes rlllhese propeller Avanesrare rotated by a slight wind fso that.Y an.a1'.ming

y by motion-oftha'sh-ipflor othenwinds, moulds-be s sui'licientrtoecause the propeller cto .rotate :land

initiate the'. 'j et, .with tliezzresult that :the .bomb dwould Abe :propelledacross Jthenieek .oi` theN canrier 50 fby the jet,`-endangering .personnelandf equipment.

`In order tri-prevent sucltiocourrenoesn the lprof j ectile -of our invention preferably Ppincludes. a safety *devicei i011l preventing: ,ignition ofi dane-- j et propellant', :untill-operated ..by `a mindlfveloeitytaof,

throughout the burning time.

3 position prevents the ignition of the jet, but does not in any way interfere with the arming of the high explosive fuze. Consequently, even though this safety device should fail to function in a live drop, the high explosive fuze would arm and the bomb would not drop as a dud.

A further object of the invention is to provide a device for igniting a jet propellant explosive, in which a charge for igniting the explosive is normally maintained in an unarmed position and is adapted to be i'lred by a striker which is normally retained in a clocked position separated from the charge. A mechanism operated by a propeller, which is rotated by the surrounding medium after the projectile is launchedfpreferably operates a cam or other means for successively moving the charge to an armed position and causing the striker to fire the charge.

The above-mentionedand other objects of the linvention will be apparent from the following specification and the accompanying drawings, in which:

Fig. l is a vertical sectional view of a portion of a bomb made in accordance with our invention, showing some of the parts in elevation;

Fig. 2 is a fragmentary detailed sectional view showing the mounting oi' the trap rod for the propellant and the bearing for the arming shaft Fig. 3 is the horizontal sectional View taken on line 3-3 of Fig. l, showing the partsY in their safe or unarmed positions with some of the parts broken away for clarity; .Fig 4 is a horizontal sectional View taken on line 4-4 of Fig. 1, showing-,the parts in their fired positions with some of the parts broken away for clarity;

. Fig. 5 is a vertical sectional view of a portion of the mechanism, showing the parts in their safe Y positions Fig. 6 is a detailed vertical sectional View of some of the parts in their red positions;

Fig. '7 is a detailed sectional View taken on line .."I .-"I of Fig. 3 and viewed reversely to Fig. 5;

Fig. 8 is a detailed elevation view of the igniting mechanism of the device, and

Fig. 9is a plan View of the device showing the arming wire in position.

v As shown in Fig.u 1, the jet propulsion device I "comprises essentially achamber in Vwhich the propellant charge I2 burned, a nozzle I3 through which the gases from the burning charge issue, Vand a fuze mechanism I4 for initiating the jet action. As illustrated, the chamber and the v nozzle I3 are formed of a single piece ofV metal vwhich is threaded on a supporting plate sel cured to the base plate I6 of the bomb I'I by :means of screws I8. Fins |9 are secured to the outer surface of the nozzle|3 for stabilizing the bomb in ilight.l A

The chamber I contains a trap for holding the propellant charge I2. This trap comprises a plurality of rods 22 screwed to a trap disc 2| at one ,end and having a twisted wormhead 23 formed at the other end for holding the propellant with- Vin the combustion chamber.

, The propellant charge y|2 comprises a plurality of grains 24fof ballistite or other suitable propellant in the form of cylinders, each having an axial perforation25 `through which the wormhead trap rod 22 is inserted to hold the grains to the disc 2|. Cylindrical grains of propellant with a single axial perforation are used in order to provide a burning surface which remainssubstantially constant That is, as the outer surface of each cylindrical grain decreases in burning, the inner surface of the grain dening the perforation 25 increases due to burning, so that the total burning surface remains substantially constant. The most important feature of the wormhead trap rod support for the propellant is that a suflicient surface is provided across the ends of the powder grains to support these grains against setback without impeding the low of gas liberated by the combustion of the exposed inner circumferential surfaces of the grains'. The trap wires 22 are secured to the disc 2| which is in turn held in place between a shoulder 26, formed in the combustion chamber I, and the rear surface of the supporting plate l5.

It is desirable to prevent the gases formed by the burning propellant from leaking around the front of the disc 2| and causing the disc to bulge and break free from its securing engagement between the shoulder 26 and the supporting plate |5, and to this end a gasket 27 formed of an asbestos a-nd metallic composition is placed between the trap disc 2| and the front plate I5 of the propulsion chamber. Bulging or'loosening of the disc 2| might result in freeing the powder traps to move rearwardly where they would clog the nozzle and prevent the flow of gas therethrough. Any such clogging of the nozzle by the trap wires or propellant material would cause the pressure within7 the combustion chamber to be built up rapidly resulting in blow-ups of the combustion chamber. Speciiically, the gasket which is preferred is formed of asbestos sheets laminated to a pierced steel reinforcement plate by means of clinched over-projecting tangs. The surfaces of this gasket are smoothed out and then coated with iinely divided graphite.

In order to prevent breaking on of the trap rods 22 at the poi-nts where they screw into the disc 2|, holes 28 of a diameter equal to the diameter of the trap rods 22, are bored into the disc 2| a distance less than the thickness of the disc, and for the remaining portion of the thickness of the plate, the holes are tapped to fit the threaded end of the trap rod 22. This is an important improvement in trapping and prevents blow-ups and high pressures resulting from the trap rods breaking off and choking the nozzle.

As illustrated in Fig. l, the base plate I6 of the 'bomb |I is adapted to accommodate a standard impact detonating fuze 30. This Vf uze may be any suitable type ofbase detonating uze which can be armed by rotation o-f a shaft 3 I, and its details are not illustrated since they are not involved in this invention. It is to be noted, however, that the base of the fuze fits flush with the rear surface of the base plate i6 except for the arming shaft 3| which protrudes therefrom. The fuze is provided with the usual percussion primer, booster charge, and ring pin inertia member (not shown). The firing pin inertia member is retained in a position spaced from the primer by suitable release mechanism which prevents the inertia member from being dislodged on impact for engagement with the primer until after the arming shaft 3| has .completed a prescribed number of revolutions. .After the arming shaft 3| has completed the necessary revolutions, the iiring pin inertia member will be free to move to engage the percussion primer on impact to set off the fuze booster for detonating the bomb.

The arming shaft 3| lis rotatable in a bearing 32 in the trap disc 2 This bearing has a flanged portion 33 which is tted into a recess 20a. cut away from the edge of the shaft opening 20 formed in the trap disc 2| (Fig.,2). The shaft AWithin thecombustion chamber be prevented from `gaining access into the fuze and thehigh explosiveswithin the boi-hb. Sealing of the shaft `3l Within the bearigSZ by means f obturating cups and the like is very diicult because the hot .propellantgases quickly erode "the sealing material. In lthe prsent invention, this scali'n'gis Hsuccessfully accomplished by`utili2i1ig-the high low pressure about -'the shaft. illustrated in rugs. '1, 5 and 6 of the drawings, shaftai vis ehclosed in a tube '34 which extends `rez'irwa'rdly` of Vthe combustion chamber past the throat of the ,nozzle s0 that its rear' end lies Withinthe nozzle flare I3 facing the direction 'of 'fluid discharge.

When the vplate 4&5 and the 'igniting mechanism are blown out on ignition of the jet, as `Will be 'explained presently, there'ar end of tube 34 is opened to the atmosphere. The ownf the propellant fluid along the tube causes a low pressure .area to'b' built up inifrontiof its openrear" end.

"Thus, even though the h'ot 'propellant iiuid were -"t'o gai'acoess intoth tube by eroding thetub'e at "its junction with 'the Lpiatezl, this fluid wohn be 'caused to 'flow toward `the low'pressure area "fr discharge throughthe jet andlwould not gain Va'icces's into the highekplosive "or its' iuze.

, As'shown in Figsfand 6, shaft 3l, which is ported'for rotation Within the'tube 34, terinates"at `a rotatable chuck 36. This chuck providesar'eleasable connection with the propeller shafty ,3,9 -which is secured to the arming propel- "lr 31. "Thus, when plate 46 and the rear mecha- Thism isejected on ignition ofthe propellant, shaft 39 'separates 'from shaft 3I` leaving the latter' in place. The `propeller hub 38 "is rotatable in a bearing 49 `formed integrally with a housing 4G.

"The` housing 43 also has'a stationary sun' vgear 44 4 "secured :to itsnndersurface andY provides aV beari'lg surface for the hub 0f a rotatable 'arm 4 l The "arm 4l is pinned or keyedto `theshaft 39 for 'rotation therewith and provides'a support for planet gears '42 and 43 Awhich .are rotatable about a longitudinal axis. The gear 42 meshes with the Vsun gear 44 and is rotated about its :axis to rotate the `pinion 'gear 43, as the arm 4l moves the gear 42 in its orbitabout the sun gear 44m response Y to rotation of the propeller 31.

1A ring gear 45 is rotatably supported within a nozzle cover plate 45 and meshes with the plan- ,tary pinion gear 43 so as to be rotated thereby. Gear 45 has one moretooth than the sun gear 44 so that Awhen the propeller 31 is rotated by air during the free fall of the boinhthe 4arm 4l 'ro- ,ta-tes the two equivalent pinion gears 42 and 43 as a planet'about thesun gear 44`and advances h the ring gear` 45 relative to sun gear 44. Assuming that sun gear 44 is provided with, thirty-mine teeth andzthat'the lringge'ar 45 has forty teeth, vthen `sincesthe sun gear 44 is held against rota- `A`tion, theplanet gears will be rotated about their axisas,theyrevolvenabout gear 44. The number of teeth on the planet gears are equal, consequentlyv the ring gear 45 will advance a distance equal to l.,onetootlfifor each complete rotation ofthe propeller. The propeller vanmust therefore revolve' v6 thirty-nine times to turn the Anhg gear 45 andthe members which rotate with it through a single revolution.

Two bell crank levers `52 and 53 are each pivoted to a support secured to the tube 34 and are spring biased by springs v520i and 53a, respectively, to a position so that followers 54 and 55, rotatably mounted on the ends of each lever, are forced into Habutting engagement with cam surfaces 50 and 5l on the peripheries of rotatable disc-like members 56 and 51, respectively, which rotate with gear 45. The end 4of the bell crank lever l52 opposite the follower 54 has a notch 58a for engaging a pin 58 carried by the end of a Vpivotecl '1, impact striker 60. A spring 6| biasesethe impact striker 60 and its firing pin 62 toward a recess 63 formed in a percussion primer cartridge housin'g 64. A percussion primer cartridge 66 is retained in a holder 65 which has two open sides and two closed sides and is rotatably supported within a housing 64. Holder 65 has an arm 61 extending transversely from an end thereof for rotating the holder. Arm 61 is engaged by a notch 68 formed in the end of the bell crank lever 53 to retain the holder 65 vand arm 61 in a displaced position against the action of a spring 69. In this displaced position, the percussion primer isdisposed substantially from its armed positio-n, and the closed sides of the holder 65 separate the primer from the firing pin and also ,The spring o9 provides the torque for rotating the holder to bring the percussion primer into impact receiving alignment With the firing pin 62 immediately upon release of the arm 61 by the bell crank lever 53. By retaining the percussion primer out of alignment with the ring pin, the igniter for the jet propellant is safe from operation by impacts which might dislodge the impact striker from its position of holding engagement with the bell crank 52.

The cams 5) and 5i are designed so that upon rotation in the direction which would result from the action of the air on the propeller in a free fall, the bell crank 53 will be lifted to release the arm 61 to permit the holder to bring the percussion primer into alignment with the ring pin prior to release of the striker from its dis- V placedY position as restrained by the bell crank lever 52. Further rotation of the discs 55 and 52 out of engagement with the striker. The

striker is now free to be driven by the spring 6I into firingI engagement with the percussion primer except for the fact that an arm 15 enga-ges the pin 58 carried by lever 6h to hold the impact member away from the primer,

Arm 15 projects from a shaft 'i8 rotatably mounted on plate 4G by means of bearings 48a and a bracket 83 to which is attached one end of a coiled spring 84. The other end of the spring is attached to a collar S5 mounted on the shaft 18, the spring tending to rotate the shaft 18 toward its unarmed position in which the arm 15 engages pin 5B. Shaft 18 is shown in its unarmed position in Figs. 3 and '1. When the bomb is launched, the air pressure on vanes 11 on the ends of shaft 18 rotates the shaft from the unarmed position to the armed position shown in Fig. 4, against the action of spring 84. Vanes 11 rotate into contact with the vane stops 51a, mounted on plate 4%, and the resulting rotation of shaft 18 moves arm 15 out of engagement with pin 58 to `the position shown in Figs. 4 and 6.

the primer 6G is fired,` upon" releaselof striker 62, the resulting blast is communicated to the propellant charges I2 through primer housing 84 and a tube 8% extendingy forwardly from the interior of the primer housing to a point adjacent the propellant charges. Accordingly, the propellant charges l2 are ignited by the primer blast so that the jet action is initiated.

Arm 'l5 provides additional safety means and prevents the jet propellant from being ignited by rotation of the propeller by normal head Winds should the arming wire t2 b-e accidentally dislodged. By virtue of the air pressure actuated arm 15, not only must the propeller complete a certain number of revolutions, but the bomb must also be in an air stream of a predetermined velocity in order for the jet to become ignited. With this construction, the hazards previously attached to the jet-accelerated bomb are eliminated, since the new device requires a predeter- Vmined minimum air velocity for operation. For

example, the tension of spring 8d may be set so y as to require a slip stream of at least 10G knots acting on Janes 'il before arm is is moved to its armed-position. Even though the vanes should fail to lift the arm 75, the base detonating fuze 30 will become armed by rotation of arming propeller 3'! and the bomb will not be a dud.

Propeller 3l is normally restrained from rotating by an arming wire 82 which is inserted through apertures in the Vanes of the propeller. A spring clamp 82a mounted on plate it holds the wire ag-ainst accidental withdrawal. This arming wire is withdrawn in any conventional manner when the bomb is launched.

Bombs are seldom if lever launched from an aircraft at velocities less than 100 knots, and

consequently the impact striker t is conditioned.Y

for release by the propeller-actuated bell crank immediately upon being launched. When the bomb is launched, the air pressure acts upon the vanes El to rotate the arm 'i5 out of its position of holding engagement with the striker, and acts also upon the propeller to rotate the pinion gears 42 and 43 about the sun gear de to drive the gear lle and discs 55 and 5l. The cam surfaces formed on the discs El' and 56 successively actuate the bell crank levers 53 and 52 which successively release the arm El for rotating the cartridge holder 5E to bring the cartridge into its armed position in alignment with the firing pin -i 62 and release the striker member t@ to permit it to be driven by the spring 6! into percussion engagement with the primer E6. A tube 80 is provided for transmitting the flash from the percussion primer into the combustion chamber to ignite the primer for the 'propellant charge.

As soon as the propellant charge is set oi, a iluid pressure is quickly built up Within the combustion chamber by the gases of combustion. This fluid pressure acts upon the nozzle cover plate to shear the .cover plate from its connection with the nozzle flare at the bolts 8i and th-us eject the operating mechanism for the igniter and fuze to clear tie jet for the high velocity discharge of the propellant uid required to accelerate the bomb. The necessity for clearing the nozzle of the operating mechanism in order to assure efciency of the jet propellant makes it necessary for the base detonating fuze 3G to be armed before the propellant charge is ignited, as explained above.

It will be understood that as the high pressure uid in the combustion chamber ll discharges through nozzle i3, the resulting reaction impulse increases the velocity of fall of the bomb and'V lil thereby increases its armor penetrating ability, The propeller 3l, operating through the planetary gearing 42. 43 and 44 and the cam 50 and lever 52, provides a time delay in ignition of the jet propellant charge l2, following the release of Athe bomb, and this delay is preferably timed so that the propellant charge is ignited when the bomb reaches a point in its normal trajectory at which the lateral component of the thrust produced by the jet is at a'minimum. Thus, the design of the time delay means will depend upon the ballistics of the bomb for which the jet propelling device is intended. By properly designing the timing means so that the jet action is initiated at the trajectory point referred to, the bomb velocity may be increased with a minimum change in its normal trajectory.

Although onespecic embodiment of the invention has been described and shown in the drawings, the invention is not to be construed as limited to that embodiment. The various features of the device such as the cartridge holder, the striker, and the safety means therefor may assume various other forms without departing s from the scope of the invention. Also, the linkages between the propeller and the various members actuated thereby may be varied over a wide range of forms.

We claim:

l. A projectile having a combustion chamber, a propellant charge in said chamber, a rearwardly opening nozzle extending from said chamber, and a time delay mechanism normally positioned in said nozzle for igniting said propellant charge, detent means normally securing against initiation of the action of said time delay mechanism and movable by an air stream of a predetermined velocity to an inoperative position, said mechanism being adapted to be expelled from said nozzle by the gases of -combustion to provide an unobstructed nozzle exit for said gases.

2. A high explosive projectile having a nose portion and a base portion, a normally unarmed fuze in said base portion for detonating the high explosive, a normally inactive jet propulsion device comprising a propellant charge, a vented chamber containing said charge conforming in configuration with said projectile when secured to the base thereof to form a tail therefor, and means carried by said tail and extending through said chamber for successively arming said fuze and initiating action of said jet propulsion device.

3. A high explosive projectile having a nose portion and a base portion, a normally unarmed fuze in said base portion for detonating the projectile, normally inactive jet propulsion means comprising a propellant charge, a vented chamber containing said charge and conforming in configuration with said projectile when secured to the base thereof to form a tail therefor, and means extending through said chamber and operable after said projectile is launched for successively arming said fuze and initiating action of said jet propulsion means.

4. A high explosive projectile having a nose 4portion and a base portion, a normally unarmed fuze in said base portion for detonating the proj ectile, normally inactive jet propulsion means including a propellant, a vented chamber containing said propellant and conforming in configuration with said projectile and secured to the base thereof to form a tail therefor, and aerodynamically operated means carried by said tail, means connectelto said-- aerodynamically operated meansV extending through said chamber for su- .cessively aiming said niegan@ initiating action of said jet propulsion means after said projectile Aly inactive' jetpropulsion means, aerodynamically operated mean'sfor successively arming said fuze and initiating action of said jet propulsion means,

and means for securing against actuation of said jet propulsion means by an air stream of less than a predetermined velocity.

v 6. In a high explosive projectile having a normally unarmed fuze for detonating the projectile, and normally inactive jet propulsion means, the combination of an aerodynamically operated mechanism for successively arming said fuze and initiating action of said jet propulsion means, and detent means normally securing against initiation of the action of said jet propulsion means and movable by an air stream of a predetermined velocity to an inoperative position.

7. In a high explosive projectile having a normally unarmed fuze for detonating the projectile and normally inactive jet propulsion means, a propeller rotatable by the ow of air when the projectile is launched, means operable by the propeller to arm said fuze, and means operable by rotation of said propeller subsequent to the arming of said fuze for initiating action of said jet propulsion means.

8. In a high explosive projectile having a normally unarmed fuze for detonating the projectile and having normally inactive jet propulsion means, an aerodynamically operated control mechanism carried by said jet propulsion means and having an operative connection extending through said jet propulsion means for successively arming said fuze and initiating action of said jet propulsion means, and means for securing against actuation of said jet propulsion means by an air stream of less than a predetermined velocity.

9. In a projectile having a normally inactive jet propulsion device, mechanism for igniting said device, including an air operated propeller, a percussion primer cartridge, a rotatably mounted holder for said cartridge, said holder being normally in an unarmed position, a striker for firing said cartridge, a cam operatively connected to said propeller, and follower means for said cam for successively rotating said holder to an armed position and causing said striker to fire said cartridge.

10. In a yprojectile having a normally inactive jet propulsion device, an air stream operated prol peller, means under the control of said propeller for igniting said device after said propeller has completed a predetermined number of revolutions, and detent means normally securing against initiation of the action of said jet propulsion device and movable by an air stream oi a Ipredetermined velocity to an inoperative position.

1l. In a high explosive projectile having a combustion chamber containing a jet propellant explosive, a fuze adjacent said chamber for detonating said projectile, and a partition between said chamber and said fuze, the combination of an air Voperated propeller, a propeller shaft extending fthrough said chamber and said partition for armving said fuze on rotation of the propeller, and means for preventing flow of the high pressure combustion gases from said propellant through said partition along said shaft.

1,2, Ina highegplosive projectile having a combustion chamber containinga jet propellant explosive for'. generating a propellant iluid, a nozzle at' the rearend of the chamber, and a fuze adjacent to ,said chamber for detonating said projectile, the combination of an air operated propeller, a shaft extending through said chamber for connecting said propeller and said fuze for arming said fuze, and-means responsive to the high velocity discharge of said propellant fluid through the nozzle for maintaining about said shaft a. uid pressure lower than the fluid pressure within said chamber, whereby said fuze is maintained isolated from the hot propellant fluid.

13. In a high explosive projectile having a combustion chamber containing a jet propellant explosive for generating a propellant fluid, a nozzle at the rear end of said chamber, and a fuze adjacent said chamber for detonating said projectile, the combination of an air operated propeller, a shaft extending through said chamber for connecting said propeller and said fuze for arming said fuze, and a tube surrounding said shaft in spaced relation thereto and opening into said nozzle, whereby the high velocity discharge of propellant fluid through said nozzle produces a low pressure within said tube to draw the hot propellant fluid which enters said tube rearwardly away from said fuze.

14. A high explosive projectile having a combustion chamber containing a jet propellant explosive for generating a propellant iiuid, a nozzle at the rear end of said chamber, a fuze adjacent to said chamber for detonating said projectile, and a partition between said fuze and said chamber, a propeller shaft extending from said fuze through said chamber, and a tube surrounding said shaft in spaced relation thereto and extending from said partition into said nozzle, said tube opening rearwardly into said nozzle, whereby the high velocity discharge of propellant iluid through said nozzle produces low pressure within said tube to draw the hot propellant fluid which may enter said tube rearwardly away from said fuze.

15. In a projectile having normally inactive jet propulsion means, mechanism for initiating action of said means comprising an air rotatable propeller, a holder for a propellant igniting charge, said holder being normally retained in an unarmed position and being biased toward its armed position, a striker for firing said igniting charge, said striker being normally retained in a cocked position and being biased toward firing engagement with said igniting charge, a cam movable by said propeller to release said holder for movement to its armed position, and a second cam movable by said propeller for releasing said striker for movement into firing engagement with said igniting charge subsequent to movement of said holder to its armed position.

16. In a high explosive projectile having a fuze, a combustion chamber containing a jet propellant explosive and a nozzle at one end of said chamber, the combination of a plate detachably mounted on the nozzle so as to substantially close said nozzle, a propeller rotatably mounted on said plate, mechanism carried by said plate and operable by rotation of said propeller for igniting said propellant explosive at a predetermined time interval after launching of the projectile, and a propeller shaft for detachable connection to the fuze for arming the fuze of the projectile by action of the propeller, whereby said plate, propeller, mechanism and shaft are adapted to be i l 112 Y expelled by the gases of combustion on ignition UNITED STATES PATENTS of said propellant explosive. Number Name Date g'LARAYNIEICE 1,959,401 WOOdbeIly May 22, `1934 RUDOLPNII3 F.' MALLINA. 5 FOREIGN PATENTS Number Country Date REFERENCES CITED 257,335 Great Britain Aug. 27, 1926 The following references are of record in the 331,496 France June 7: 1933 le of this patent: 543,739 Great Britain Mar. 11, 1942 

